This invention relates to laser light switching technology.
Optical fiber laser light switching devices currently used generally rely upon rotating or moving mirrors or translating optical fibers to permit the selective injection of high peak power laser light into multiple fibers. These devices typically have lack of reproducibility in the alignment of focused laser light onto the faces of the optical fibers, leading to laser energy losses or optical damage to the optical fiber ends. Since they contain moving mechanical parts, the lifetimes of these devices are limited and they eventually fail due to mechanical wear. Also, electro-optical laser light switching devices that depend upon waveguide technology have speeds which are limited by the time required for deformation and recovery of a piezoelectric crystal (many milliseconds); thus, the rate at which light can be switched from one fiber to another is similarly limited.
There is a need for faster, more durable, accurate, reliable optical fiber switching devices with high power light handling capabilities.
Therefore it is an object of this invention to provide a method and apparatus for laser light optical fiber switching.
It is also an object of this invention to provide a method and apparatus for laser light optical fiber switching which can be used for sequential energizing of optical ignitors for aviation turbine engines.
It is another object of this invention to provide a method and apparatus for laser light optical fiber switching which can be used for sequential ignition of more than one internal combustion fuel engine cylinder.
It is yet another object of this invention to provide a method and apparatus for laser light optical fiber switching which does not require use of waveguide technology.
It is a further object of this invention to provide a method and apparatus for laser light optical fiber switching which is useful for communications industry applications.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims and is intended to cover all changes and modifications within the spirit and scope thereof.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, there has been invented a device which employs an alternating sequence of laser light modulators, such as Pockels cells, and laser light polarizers to distribute laser light for injection into a plurality of optical fibers. This invention is particularly useful for sequential ignition of a number of internal combustion engine cylinders or turbine engine ignitors.
In the present invention an optical fiber laser light switching device has at least one laser light modulator positioned and operated so as to direct light from a laser into at least one laser light polarizer which either transports or rejects the laser light depending upon the polarization of the laser light, with laser light reflecting mirrors positioned so as to direct the rejected light through a first focusing lens into a first optical fiber and a second focusing lens to focus the laser light transported by the polarizer into a second optical fiber.
Alternatively, laser light distribution can be controlled mechanically rather than electro-optically by using waveplates to change the linear polarization of the laser light.
The invention also provides for laser light switching by:
(a) directing laser light from a laser through a laser light modulator;
(b) applying a voltage to the laser light modulator intermittently in accordance with signals from a timing module, thereby controlling the polarization of the laser light;
(c) directing the laser light from the laser light modulator into a laser light polarizer which either rejects or transports the laser light according to whether or not the laser light has been appropriately polarized by the laser light modulator;
(d) directing any the laser light which is rejected by the laser light polarizer through a first focusing lens into a first optical fiber;
(e) directing any of the laser light which is transported by the laser light polarizer through a second focusing lens into a second optical fiber;
thereby sequencing injections of laser light into a plurality of optical fibers.
The invention can be operated electro-optically with no need for any mechanical or moving parts, or, alternatively, can be operated electro-mechanically. The invention can be used to switch either pulsed or continuous wave laser light.